In a traditional steam engine a cylinder is provided in which a piston is moved backwards and forwards by the pressure of steam applied alternately to the two faces of the piston. It is also known that steam exits the cylinders with unused energy. Prior engines have utilized 2, 3, or even 4 cylinders with pistons connected to a common shaft. These are arranged such that the steam leaving the first cylinder enters and powers the next cylinder, which is of larger diameter and similarly passing thereafter to larger diameter cylinders and finally escaping into a condensing chamber or the atmosphere. However, even compound steam engines utilize only a portion of the energy available.
With respect to internal combustion engines, and as an example four stroke high compression gasoline engines, despite numerous attempts at improving the conversion ratio of heat energy into mechanical energy, much of the energy is wasted. While the internal combustion gasoline engine is more efficient than a steam engine, it only transforms about 30% of its heat energy into mechanical energy. This is in part due to losses in cooling the engine and through the exhaust. Further, internal combustion engines create a large amount of pollutants. Finally, conventional internal combustion engines, due to the thermodynamic properties of the combustion mixture of fuel and air, are not capable of creating high power or torque at low rpms. Thus, when pulling a heavy load up a hill a vehicle driver must shift to a lower gear to raise the rpms.
Possible benefits derived from the use of water in conjunction with internal combustion engines have been recognized. There has been experimentation with the concept of water injection into combustion air. However, these experiments have been only partially successful since, when water is injected into the combustion air it interferes with the ignition and combustion of the fuel/air charge in the cylinder head.
It is therefore an object of this invention to provide an internal combustion engine having a greater heat energy/mechanical energy conversion ratio than is presently available in known engines.
A further object is to provide an engine which will produce less harmful pollutants than are produced in conventional internal combustion engines.
A still further object is to create an engine that is able to produce high power and torque at lower rpms than in conventional internal combustion engines.
Finally, it is an object of the invention to create the desired engine which is built from standard engine parts with little modification.
The invention achieves these objectives by providing an engine which combines desirable qualities of the internal combustion engine with desirable qualities of the steam engine. The steam, which provides most of the engines' power, is generated in the cylinder head after combustion takes place as the piston is forced downwards. As soon as the fuel/air charge is combusted an optimal amount of water is injected into the cylinder head. The water which is heated to the same temperature as that of the combustion charge changes to superheated steam. The heat required is provided by the combustion charge, causing the combustion gases to decrease in volume and temperature. The increased volume of the steam is greater than the decreased volume of the combustion gases. Therefore, greater power is created by the heat transfer. The steam continues to expand with reduced pressure during the remainder of the power stroke.
The vaporization of the water results in a decrease in temperature in the combustion gasses. The injected water cools the cylinder head thus reducing the possibility of the engine overheating. To help ensure that the engine will not overheat a sensor is used whereby the engine is stopped if the water supply fails. A further benefit of cooling the combustion charge immediately after combustion, is that the production of nitrogen oxides are reduced, since the time during which the high temperatures required for production of those pollutants is maintained in the cylinder heads, is reduced.
The power of the internal combustion steam engine depends on the total heat of the combustion charge, and not on the compression ratio of the cylinders. Therefore a large diameter cylinder which burns a low octane, low heat combustion charge can produce the same power as a smaller diameter cylinder with a high compression ratio, which burns a high octane fuel. Therefore, the same power can be produced at a lower initial temperature.
Finally, the internal combustion steam engine allows for the generation of high power and torque at low engine speeds due to the increased power generated by the expansion of the water/steam. The mechanical power produced by a piston is dependant upon the length of stroke of the piston, and the mean, effective pressure of the gases on the face of the piston. In conventional high speed, high compression engines most of the power is generated in the first inch of the power stroke of the pistons. High speed is therefore necessary to create high power. The internal combustion steam engine which is designed as a slow running, long stroke engine will produce more power at low rpms and produce less vibrations than high speed engines.
Another important feature of the internal combustion steam engine is the importance of transferring substantially all of the heat from the exhaust gases to the combustion air.
Finally a plurality of compound cylinders also helps to use a greater proportion of the steam energy.